"Apollo 15 lunar module pilot Jim Irwin loaded the lunar rover with tools and equipment in preparation for the first lunar spacewalk at the Hadley-Apennine landing site. The Lunar Module 'Falcon' appears on the left in this image. The undeployed Laser Ranging Retro-Reflector lies atop Falcon's Modular Equipment Stowage Assembly.

Apollo 15 launched 40 years ago today on July 26, 1971, from Launch Pad 39A at the Kennedy Space Center."

(CNN) - Apparently, there's a bit of Neanderthal in many of us, according to a newly released study.

Research says modern humans of non-African heritage have distant genetic ties to Neanderthals - cousins of modern humans who went extinct 30,000 years ago.

Published in Oxford Journals' "Molecular Biology and Evolution," the study backs up previous theories that humans and Neanderthals mated and had offspring.

The research is based on analysis of more than 6,000 DNA samples gathered from all populated continents.

In most of the samples, part of the human X chromosome called the haplotype shared a DNA sequence with the Neanderthal genome, said University of Montreal Professor Damian Labuta, who lead the study for CHU Sainte-Justine Research Center. But the Neanderthal sequence was not present in haplotype taken from people with sub-Saharan African heritage.

Neanderthals lived in what is now western Eur-Asia including parts of Germany, France, Spain, Russia and Croatia. Their ancestors left Africa at least 400,000 years ago, which likely explains why humans with African heritage don't have Neanderthal-linked chromosomes.

"Astronaut Gus Grissom climbs into his 'Liberty Bell 7' spacecraft on July 21, 1961. The Mercury-Redstone 4 rocket successfully launched the Liberty Bell 7 at 7:20 a.m. that morning. This was the second in a series of successful U.S. manned suborbital flights."

Is there water in space? Well, 12 billion years ago there was a lot of it, astronomers say.

A team of international scientists analyzing a quasar 12 billion light-years from Earth say there is water vapor in the object - which they call "a voraciously feeding black hole" - equivalent to 34 billion times the mass of our planet. They say it's the largest mass of water ever found.

The discovery shows water was present in the early stages of the universe when it was 1.6 billion years old, researchers say. The big-bang theory puts the age of the universe at 13.6 billion years.

In our galaxy, the Milky Way, there is 4,000 times less water than in the quasar, and it is spread over a few light-years, according to the study. But in the quasar, the water vapor is present over hundreds of light-years, they said. A light-year is about 6 trillion miles.

The discovery was made using a spectrograph at the California Institute of Technology's telescope on the Mauna Kea volcano on Hawaii's Big Island and verified using a facility in California's Inyo Mountains.

Besides the University of Colorado-Boulder and Caltech, NASA's Jet Propulsion Laboratory, Japan's Institute of Space and Astronautical Science, the Observatories of the Carnegie Institute of Science and the University of Pennsylvania participated in the research.

Could there have been life on Mars? That's the mission NASA is setting out to answer with Curiosity, the next-generation Mars rover whose landing site was announced Friday at the National Air and Space Museum's annual Mars Day.

"Workers measured and marked in bright red the letters "MLG" at the spot where space shuttle Atlantis' main landing gear came to rest after the vehicle's final return from space. Securing the space shuttle fleet's place in history on the STS-135 mission, Atlantis safely and successfully rounded out NASA's Space Shuttle Program on the Shuttle Landing Facility's Runway 15 at Kennedy Space Center in Florida. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m.

On the 37th shuttle mission to the International Space Station, STS-135 delivered more than 9,400 pounds of spare parts, equipment and supplies in the Raffaello multi-purpose logistics module that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles."

Editor's note:Meg Urry is director of the Yale Center for Astronomy & Astrophysics and the chair of the Yale physics department. Her nearly three-decade career of space study includes a 14-year stint at the the Space Telescope Science Institute, the home of the Hubble Space Telescope, where she headed the Space Science Selection Office, sifting through thousands of applications from scientists each year hoping to use the telescope. This piece was written in association with The Op-Ed Project, an organization seeking to expand the range of opinion voices to include more women.

(CNN) - Atlantis, the last space shuttle, returned to Earth on Thursday and will go to its post-retirement gig at the Kennedy Space Center Visitor Complex. After more than 30 years and 135 shuttle flights by literally hundreds of astronauts, NASA has reason to be proud.

But for any terrestrial mourners out there, I have some tissues and another perspective: It's time.

The shuttle is an aging workhorse that should be put to pasture - it's time for a new direction for the space program.

The private sector should take over routine spaceflight while NASA develops new, more technologically current vehicles that can carry human explorers well beyond low Earth orbit.

Just as importantly, NASA should continue its wildly successful program of robotic space science, which has returned an incredible wealth of knowledge for pennies on the human-spaceflight dollar.

Every Friday, @CNNLightYears will suggest interesting and exciting space and science Twitter accounts to follow.

Today, @CNNLightYears is giving a #FollowFriday to the Smithsonian Institution, the world's largest museum and research complex. The Smithsonian Institution includes 19 museums and galleries, nine research centers, and the National Zoo.

@Smithsonian
The official account of the Smithsonian Institution tweets about exhibits and history tidbits, as well as interacts with museum goers.

@airandspace
The Smithsonian Institution National Air and Space Museum tweets about historical events, posting "today in . . ." tweets. @airandspace also shares current museum events like Mars Day (which just so happens to be today).

@chandraxray
Chandra X-Ray Observatory tweets about new findings from studying black holes, stars, and clusters of galaxies. Follow @chandraxray for tweets about new discoveries and explanations of our universe.

@NationalZoo
The Smithsonian National Zoological Park tweets about its huge collection of animals, such as the zoo's first whooping crane since 1923. @NationalZoo also lets followers know about live zoo cameras, such as the one that shows seven black-footed ferret babies.

@NMNH
The Smithsonian National Museum of Natural History lets followers know about exhibits, offering "Daily Dose of Science" and "Fun Fact Friday" tweets.

For a list of all Smithsonian Institution Twitter accounts, click here.

"Space shuttle Atlantis' bright-white, iconic frame illuminates the darkness as it touches down on the Shuttle Landing Facility's Runway 15 at NASA's Kennedy Space Center in Florida for the final time.

Securing the space shuttle fleet's place in history, Atlantis marked the 26th nighttime landing of NASA's Space Shuttle Program and the 78th landing at Kennedy. Main gear touchdown was at 5:57:00 a.m. EDT, followed by nose gear touchdown at 5:57:20 a.m., and wheelstop at 5:57:54 a.m.

On board are STS-135 Commander Chris Ferguson, Pilot Doug Hurley, and Mission Specialists Sandra Magnus and Rex Walheim. On the 37th shuttle mission to the International Space Station, STS-135 delivered more than 9,400 pounds of spare parts, equipment and supplies in the Raffaello multi-purpose logistics module that will sustain station operations for the next year. STS-135 was the 33rd and final flight for Atlantis, which has spent 307 days in space, orbited Earth 4,848 times and traveled 125,935,769 miles."

When Atlantis landed today, an era came to an end. The United States has been flying the space shuttle for thirty years, and for at least as long, crews have been receiving wake-up calls from Mission Control at the beginning of each flight day. The calls often include music, dialogue, and personal messages for the crew.

Atlantis' final flight included some big names personally wishing the crew good morning ending with today's final poignant wake up call of "God Bless America."

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Light Years strives to tell the stories of science research, discovery, space and education. This is your go-to place on CNN.com for today’s stories, but also for a scientific perspective on the news and everyday wonders. Come indulge your curiosity in all things space and science related, brought to you by the entire CNN family.